• tetris11@lemmy.ml
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    23 hours ago

    I went on a Bat Walk last week. It was a few of us, walking around the park a little after sunset, pointing our radios at rotted trees and tuning it to frequencies of 45-65Khz. You could hear the bats with their popping sounds before you saw them, tiny things snatching up insects off the surface of the water… incredible maneuverability

    The park ranger had this USB sonar device hanging off his phone, which scanned the entire frequency range in fixed bins of about 5Khz or so to produce a living heatmap, and used it to identify the types of bats that we were hearing and just about seeing: Common and Soprano Pippistrellas, and some Noctules.

    (src: https://www.researchgate.net/figure/Peak-frequency-and-signal-duration-for-eight-bat-species-emitting-QCF-quasi-CF-pulses_tbl1_313207046)

    It was just a group of us, huddled in silence listening to the crackle and pops of these little guys feasting for their late evening breakfast on our radios. It was pretty magical

    • Orygin@sh.itjust.works
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      18 hours ago

      Can your “radio” be called that if they listen for sonic pulses ?
      I thought the term radio was exclusive to electromagnetic radiation, does the term also apply for sonars ?
      Or maybe bats also use some kind of EM waves to echo locate too ?
      Edit: not trying to be pendantic, I’m genuinely curious about this

      • tetris11@lemmy.ml
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        18 hours ago

        It is a radio though, no? If I tune in to 95.8 Khz to access Capitol FM’s (bad) music, I’m hearing that radio band downshifted to 5-20 KHz on my speakers to make it audible for me.

        It’s the same principle I thought for bats, I’m just tuning in to lower frequencies.

        • echolalia@lemmy.ml
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          14 hours ago

          pushes glasses up nose well actually,

          Radiowaves are electromagnetic radiation (like visible light and microwaves). Sound waves are kinetic motion between air molecules. Your music radio is receiving electromagnetic waves and converting to sound waves through the radio speakers.

          I’m not a biologist or a linguist but I think its perfectly reasonable to call a device that captures inaudible sound a radio. But it is different than your music radio.

          • tetris11@lemmy.ml
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            13 hours ago

            Huh. Mind blown. I guess that explains why a regular phone with radio capabilities couldn’t pick up the bat calls without an extra device.

            I do recall we had to point the “radios” at the source we were trying to capture, so I guess it’s a sonar of sorts?